Graphics

The graphics backend interface, renderer, images and custom drawing. More...

Topics
	Vulkan backend
	The Vulkan graphics backend, and sharing a host's device and images.

Classes
class	tachyon::Buffer
class	tachyon::CustomDrawContext
	Passed to custom-draw callbacks (ElementStorage::AddCustomDraw / AddCustomDrawAfter): geometry lookups and drawing calls in a current space the callback switches with SetSpace or SetSpaceRaw, also between calls. More...
class	tachyon::PostLayoutContext
	Context for post-layout callbacks (AddPostLayout). More...
class	tachyon::GraphicsContext
	A graphics backend: the device, the window contexts that render the GUI's windows, and the images and text atlases they draw with. More...
class	tachyon::Image
	An image made by GraphicsContext::CreateImage; the backend defines its contents. More...
class	tachyon::ImageSet
	The images the shaders can sample, each at an ImageIndex. Implemented by the backend. More...
struct	tachyon::PrimitiveRenderPass
	One contiguous same-kind run of primitives, drawn with one call; or, with replay set, a cached scope's draw (its own passes), and the other fields unused. More...
struct	tachyon::PrimitiveRenderTarget
class	tachyon::PrimitiveRenderer
struct	tachyon::glsl_float4
struct	tachyon::Box
struct	tachyon::Glyph
struct	tachyon::Dot
struct	tachyon::Line
struct	tachyon::Triangle
struct	tachyon::Quad
struct	tachyon::Circle
	A circle outline: the ring lineWidth wide around center at radius, its color and dashes running clockwise from the right (+x towards +y), as LineStyle sets them. More...
struct	tachyon::Occluder
	Depth only: marks pos/size as covered by opaque content drawn after it, so what was drawn before under it is skipped (its fragments fail the depth test early). More...
struct	tachyon::PrimitiveSpec
struct	tachyon::GPUDrawPushConstants
struct	tachyon::LineStyle
class	tachyon::GUIRenderer
struct	tachyon::RHI::GpuPipeline
struct	tachyon::RHI::UploadRequest
class	tachyon::RHI::RenderDevice
	Device-lifetime operations. More...
class	tachyon::RHI::RenderCommandList
	One frame's recording surface for one window. More...
class	tachyon::NullGraphicsContext
	A graphics backend that draws nothing: the UI is built, laid out and recorded as usual, but no GPU is used and windows stay empty. More...

Typedefs
using	tachyon::PipelineSet = std::array<RHI::GpuPipeline, kPrimitiveKindCount>
using	tachyon::DeviceAddress = uint64_t
	Shader-visible buffer address.
using	tachyon::RHI::ResidentBufferId = uint64_t
	GPU storage kept across frames (UploadResidentBuffers); 0 is none.

Enumerations
enum class	tachyon::DrawSpace : uint8_t { tachyon::DrawSpace::Local , tachyon::DrawSpace::Screen }
	The coordinate space a CustomDrawContext draws in. More...
enum class	tachyon::DeviceScope { tachyon::DeviceScope::Frame , tachyon::DeviceScope::Application }
	When a deferred GPU resource destruction runs: Frame once the frames that may use it are done, Application at Cleanup. More...
enum class	tachyon::GraphicsAPI : uint8_t { tachyon::GraphicsAPI::None , tachyon::GraphicsAPI::Vulkan }
	The graphics API a backend presents with; window backends create their windows to match (SDL: SDL_WINDOW_VULKAN). More...
enum class	tachyon::ImageFormat {   tachyon::ImageFormat::UNDEFINED , tachyon::ImageFormat::R8 , tachyon::ImageFormat::R8_SRGB , tachyon::ImageFormat::R8G8 ,   tachyon::ImageFormat::R8G8_SRGB , tachyon::ImageFormat::R8G8B8 , tachyon::ImageFormat::R8G8B8_SRGB , tachyon::ImageFormat::R8G8B8A8 ,   tachyon::ImageFormat::R8G8B8A8_SRGB }
	Pixel formats for GraphicsContext::CreateImage, 8 bits per channel. More...
enum class	tachyon::Sampler { tachyon::Sampler::UNDEFINED , tachyon::Sampler::NearestRepeat , tachyon::Sampler::LinearRepeat , tachyon::Sampler::LinearClampToEdge }
	How an image is filtered and addressed when sampled. More...
enum	tachyon::ImageIndex : uint32_t { tachyon::Invalid = 0 }
	Index of an image in the graphics context's image set, as the shaders sample it. More...
enum class	tachyon::PrimitiveKind : uint8_t {   tachyon::PrimitiveKind::Box = 0 , tachyon::PrimitiveKind::Glyph , tachyon::PrimitiveKind::Dot , tachyon::PrimitiveKind::Line ,   tachyon::PrimitiveKind::Triangle , tachyon::PrimitiveKind::Quad , tachyon::PrimitiveKind::Circle , tachyon::PrimitiveKind::Occluder ,   tachyon::PrimitiveKind::Count }
enum class	tachyon::PrimitiveShape : uint8_t { tachyon::PrimitiveShape::Quad , tachyon::PrimitiveShape::Triangle }
	The vertices a primitive's vertex shader is run for; gl_VertexIndex divided by their count is the primitive, the remainder the corner. More...
enum class	tachyon::TriangleEdges : uint8_t { tachyon::TriangleEdges::None = 0 , tachyon::TriangleEdges::Edge01 = 1 << 0 , tachyon::TriangleEdges::Edge12 = 1 << 1 , tachyon::TriangleEdges::Edge20 = 1 << 2 }
	A triangle's edges, for the ones drawn without a soft edge: where it meets another triangle of the same shape (a polygon's fan), so no seam shows between them. More...
enum class	tachyon::RHI::ResidentState : uint8_t { tachyon::RHI::ResidentState::Gone , tachyon::RHI::ResidentState::Pending , tachyon::RHI::ResidentState::Ready }
	Where a resident buffer is. More...

Functions
int32_t	tachyon::SnapPx (float v)
	Round half up, the same rule the box shader uses.
IntRect	tachyon::SnapAbsolute (float4 px)
	A box with no snapped parent: each edge to the nearest pixel.
float4	tachyon::PixelBounds (const float3x2 &toPixels, IntRect r)
	The bounds of a rect mapped to window pixels, { x0, y0, x1, y1 }.
IntRect	tachyon::SnapToParent (float4 parentPx, IntRect parentSnapped, float4 childPx)
	A nested box: each edge keeps its rounded distance from the parent's snapped edge on the same side.

Variables
constexpr float	tachyon::kPrimitiveDepthStep = 1.0f / float(1 << 22)
	The depth between two primitives drawn one after the other; past the depth range all are at the nearest depth.
constexpr size_t	tachyon::kPrimitiveKindCount = size_t(PrimitiveKind::Count)
constexpr PrimitiveSpec	tachyon::kPrimitiveSpecs [kPrimitiveKindCount]
	Push-constant slot order matches the GLSL push block (box, glyph, dot, line, triangle).

Detailed Description

The graphics backend interface, renderer, images and custom drawing.

Typedef Documentation

PipelineSet

using tachyon::PipelineSet = std::array<RHI::GpuPipeline, kPrimitiveKindCount>

#include <gui_core/graphics/gui_primitive_renderer.h>

DeviceAddress

using tachyon::DeviceAddress = uint64_t

#include <gui_core/graphics/gui_render_primitives.h>

Shader-visible buffer address.

uint64_t on every modern API (VkDeviceAddress / D3D12_GPU_VIRTUAL_ADDRESS / MTLGPUAddress).

ResidentBufferId

using tachyon::RHI::ResidentBufferId = uint64_t

#include <gui_core/graphics/gui_rhi.h>

GPU storage kept across frames (UploadResidentBuffers); 0 is none.

Enumeration Type Documentation

DrawSpace

enum class tachyon::DrawSpace : uint8_t

strong

#include <gui_core/graphics/gui_custom_draw_context.h>

The coordinate space a CustomDrawContext draws in.

Enumerator
Local	The default: the registered element's content space, (0,0) at its padding box's top-left. Its contentTransform (a node view's pan and zoom) and every ancestor's apply when drawing.
Screen	Absolute layout pixels: the space of stored element rects and event.state.screenPos.

DeviceScope

enum class tachyon::DeviceScope

strong

#include <gui_core/graphics/gui_graphics_context.h>

When a deferred GPU resource destruction runs: Frame once the frames that may use it are done, Application at Cleanup.

Enumerator
Frame
Application

GraphicsAPI

enum class tachyon::GraphicsAPI : uint8_t

strong

#include <gui_core/graphics/gui_graphics_context.h>

The graphics API a backend presents with; window backends create their windows to match (SDL: SDL_WINDOW_VULKAN).

Enumerator
None	nothing is presented (NullGraphicsContext)
Vulkan

ImageFormat

enum class tachyon::ImageFormat

strong

#include <gui_core/graphics/gui_image.h>

Pixel formats for GraphicsContext::CreateImage, 8 bits per channel.

The _SRGB formats decode sRGB to linear when sampled.

Enumerator
UNDEFINED
R8
R8_SRGB
R8G8
R8G8_SRGB
R8G8B8
R8G8B8_SRGB
R8G8B8A8
R8G8B8A8_SRGB

Sampler

enum class tachyon::Sampler

strong

#include <gui_core/graphics/gui_image.h>

How an image is filtered and addressed when sampled.

Enumerator
UNDEFINED
NearestRepeat
LinearRepeat
LinearClampToEdge

ImageIndex

enum tachyon::ImageIndex : uint32_t

#include <gui_core/graphics/gui_image.h>

Index of an image in the graphics context's image set, as the shaders sample it.

Invalid (0) is no image.

Enumerator
Invalid

Examples

host_device/host_device.cpp.

PrimitiveKind

enum class tachyon::PrimitiveKind : uint8_t

strong

#include <gui_core/graphics/gui_render_primitives.h>

Enumerator
Box
Glyph
Dot
Line
Triangle
Quad
Circle
Occluder
Count

PrimitiveShape

enum class tachyon::PrimitiveShape : uint8_t

strong

#include <gui_core/graphics/gui_render_primitives.h>

The vertices a primitive's vertex shader is run for; gl_VertexIndex divided by their count is the primitive, the remainder the corner.

Enumerator
Quad	4 corners of its rectangle, drawn as two indexed triangles (0,1,3, 0,3,2)
Triangle	3 corners of one triangle around its shape (clipped per fragment)

TriangleEdges

enum class tachyon::TriangleEdges : uint8_t

strong

#include <gui_core/graphics/gui_renderer.h>

A triangle's edges, for the ones drawn without a soft edge: where it meets another triangle of the same shape (a polygon's fan), so no seam shows between them.

Enumerator
None
Edge01	p0 to p1
Edge12	p1 to p2
Edge20	p2 to p0

ResidentState

enum class tachyon::RHI::ResidentState : uint8_t

strong

#include <gui_core/graphics/gui_rhi.h>

Where a resident buffer is.

Enumerator
Gone	released, or never made (or lost with its device)
Pending	its copy to the GPU isn't recorded yet: it can't be drawn from this frame
Ready	on the GPU: draws recorded from now on can read it

Function Documentation

SnapPx()

int32_t tachyon::SnapPx ( float v )

inline

#include <gui_core/graphics/gui_pixel_snap.h>

Round half up, the same rule the box shader uses.

SnapAbsolute()

IntRect tachyon::SnapAbsolute ( float4 px )

inline

#include <gui_core/graphics/gui_pixel_snap.h>

A box with no snapped parent: each edge to the nearest pixel.

PixelBounds()

float4 tachyon::PixelBounds ( const float3x2 & toPixels, IntRect r )

inline

#include <gui_core/graphics/gui_pixel_snap.h>

The bounds of a rect mapped to window pixels, { x0, y0, x1, y1 }.

SnapToParent()

IntRect tachyon::SnapToParent ( float4 parentPx, IntRect parentSnapped, float4 childPx )

inline

#include <gui_core/graphics/gui_pixel_snap.h>

A nested box: each edge keeps its rounded distance from the parent's snapped edge on the same side.

Variable Documentation

kPrimitiveDepthStep

float tachyon::kPrimitiveDepthStep = 1.0f / float(1 << 22)

inlineconstexpr

#include <gui_core/graphics/gui_render_primitives.h>

The depth between two primitives drawn one after the other; past the depth range all are at the nearest depth.

kPrimitiveKindCount

size_t tachyon::kPrimitiveKindCount = size_t(PrimitiveKind::Count)

inlineconstexpr

#include <gui_core/graphics/gui_render_primitives.h>

kPrimitiveSpecs

PrimitiveSpec tachyon::kPrimitiveSpecs[kPrimitiveKindCount]

inlineconstexpr

#include <gui_core/graphics/gui_render_primitives.h>

Initial value:

                                               = {
     { "box_shader",      sizeof(Box),      0 },
     { "glyph_shader",    sizeof(Glyph),    1 },
     { "dot_shader",      sizeof(Dot),      2, PrimitiveShape::Triangle },
     { "line_shader",     sizeof(Line),     3 },
     { "triangle_shader", sizeof(Triangle), 4 },
     { "quad_shader",     sizeof(Quad),     4 },
     { "circle_shader",   sizeof(Circle),   3 },
     { "occluder_shader", sizeof(Occluder), 0, PrimitiveShape::Quad, true },
}

Push-constant slot order matches the GLSL push block (box, glyph, dot, line, triangle).

The block is exactly 128 bytes, with no room for more addresses, so Quad shares the Triangle slot, Circle the Line slot and Occluder the Box slot: each pass writes its own buffer address into its slot before drawing, and a draw call holds one kind.